One concern that I have for USDT is if the SEC would classify this stablecoin as a security. I know that they are possibly working on that case, but let’s just hope that SEC would not target USDT next. I know that XRP has gone down the wire because of their pending lawsuit from the US SEC, but USDT’s collapse would be total chaos for Bitcoin, Ethereum and other cryptocurrencies.
Is this really the only concern that you have?

My concern would be that USDT is not backed. Even if they were backed my concern would be that they lied about being backed! This is a serious red flag that completely disqualifies USDT in my eyes.
I know that many people here think that since tether people were doing fine for the last 2 years they will continue to be and keep printing money indefinitely but it doesn't work like this!
The majority of Tether users don't know shit regarding what you are talking about: find me somebody who uses USDT consciously knowing all you wrote. You will not find many people aware of the USDT bomb. That's okay, bitcoin will live even after Tether's death and I am also fine with it.